You may be mostly right about the downsides of an AMEX card, but in my experience with their customer service it has been nothing short of excellent.

I'm holding out for the 30k SPG AMEX bonus to come around again, then this card will become my primary card.

I've tried to juggle cards to maximize benefits, but I've found that I forget to use one card or I forget the category for extra cash back. That's why I see the SPG AMEX as the "best" credit card....it's simple. Just use that card everywhere AMEX is accepted. Transfer your SPG points to the airline of your choice and redeem for international F tickets and your getting a return of closer to 3% or 4% without the hassle of micromanaging which credit card you use.